The subject matter herein relates generally to solar junction boxes for solar panels.
Photovoltaic (PV) modules or arrays, such as solar panels, produce electricity from solar energy. Electrical power produced by PV modules reduces the amount of energy required from non-renewable resources such as fossil fuels and nuclear energy. Significant environmental benefits are also realized from solar energy production, for example, reduction in air pollution from burning fossil fuels, reduction in water and land use from power generation plants, and reduction in the storage of waste byproducts. Solar energy produces no noise, and has few moving components. Because of their reliability, PV modules also reduce the cost of residential and commercial power to consumers.
PV cells are essentially large-area semiconductor diodes. Due to the photovoltaic effect, the energy of photons is converted into electrical power within a PV cell when the PV cell is irradiated by a light source such as sunlight. PV cells are typically interconnected into solar modules that have power ranges of up to 100 watts or greater. For large PV systems, special PV modules are produced with typical power range of up to several 100 W. A photovoltaic module is the basic element of a photovoltaic power generation system. A PV module has many solar cells interconnected in series or parallel, according to the desired voltage and current parameters. PV cells are connected in series and placed between a back sheet on the bottom and a glass layer on the top. PV cells are interconnected with thin contacts, such as a foil, on the semiconductor layer. The foil is terminated to a junction box, which may electrically connect groups of the PV cells and/or solar panels.
The junction box is typically connected to the back side of the solar panel, such as to the back sheet. The foil exits the semiconductor layer and is terminated to a corresponding terminal in the junction box. However, sealing of the junction box and/or foil are problematic. Additionally, the junction box may block some of the light, reducing the efficiency of the PV module. For example, some PV modules are bifacial panels where reflected sunlight is collected at the backside. Such bifacial panels use a glass layer as the back sheet (e.g., dual glass layer panel) to allow the sunlight to pass through the back sheet to the PV cells at the semiconductor layer. The junction box blocks the reflected sunlight at the backside. Additionally, it is costly to route the foil through the glass layer at the backside, such as by drilling a hole or slot in the glass layer. At least some known PV modules exit the foil at the edge of the solar panel. Heretofore, terminating junction boxes at such locations has proven problematic. For example, portions of the foil are exposed and susceptible to damage and water ingress. Additionally, the glass panels may have various thicknesses and thus no universal solution has been provided for terminating junction boxes to such solar panels.